My budgie was diagnosed with scaly face mites about 6 to 8 weeks ago,had 2 treatments of ivermectin and things were clearing up but now they have returned it looks like.He's by himself,i have no other animals, cleaned the cage,removed perches,etc,so why would he have gotten them again?Did he need more than 2 doses of ivermectin or i didnt clean anything other than the cage?What are reasons why mites return to a bird thats by himself and around no other animals?Thanks!